Project: Improvement of differentiation and survival rate of transplanted dopaminergic neurons via secreted neurotrophic factors (EU, MWK-Niedersachsen for Prof. Dr. Claufia Grothe)
Parkinson´s disease is a neurodegenerative disorder, caused by a progressive loss of dopaminergic neurons in the substantia nigra. One possible treatment is a curative cell therapy, in which new dopaminergic cells are implanted into the striatum. The quality of the transplants can be further improved by applying neurotrophic factors. Some of those secreted factors such as FGF8b, SHH, WNT1 are known to regulate dopaminergic neurogenesis during embryonic development.
Our group investigates the differentiation of neuronal progenitor cells (isolated from rat embryos) towards dopaminergic neurons initially in vitro. Genetic modification of those cells either by transfection or nucleofection with suitable expression plasmids (Cesnulevicius et al. 2006 Stem Cell 24: 2776), allows studying the effects of single or a combination of neurotrophic factors. Utilisation of a different promoter resulted in an improved expression level of such factors, or as shown in the figure of the enhanced green fluorescent protein (EGFP), in vitro and also in vivo.
A similar approach, co-transplantation of FGF2 transfected Schwann cells and dopaminergic neurons, showed an improved functionality of the transplants in vivo (Timmer et al. 2004 Exp. Neurol. 187: 118). For such experiments we are using an animal model of Parkinson´s disease, more precisely the unilateral 6-OHDA-lesioned rat model (Timmer et al. 2006 Neurobiol. Dis. 21: 587).
Project: Relevance of the FGF system for the development of dopaminergic neurons in the midbrain
Previous investigation of adult mouse mutants defective for fibroblast growth factor 2 (FGF2) or FGF-receptor 3 (FGFR3) revealed differences in the volume of the substantia nigra and the cell number of dopaminergic neurons (Timmer et al. 2007 J. Neurosci. 27: 459). In continuation of this work we analyse the development of the substantia nigra during embryonic (E14), newborn (P0) and postnatal stages with several approaches.
Second, a cell culture model of the ventral mesencephalon is used to compare the different mouse mutants. Besides FGF2 several other FGFs (e.g. FGF8b) are known to regulate dopaminergic differentiation (for review see Grothe und Timmer 2007 Brain Res. Rev. 54: 80). By adding growth factors (as recombinant protein or via transfection with suitable expression plasmids) we investigate their relevance for the dopaminergic differentiation in vitro.
Project: In vitro studies to characterize matrix qualities of simple and complex polySia-based materials
The biological effects of PolySia and PolySia-based materials on cultures of primary Neurons and peripheral glia (Schwann cells) ist evaluated in vitro. Evaluated Neurons are: sensory dorsal root ganglia neurons from neonatal rats, motoneurons from embryonic rat spinal cord or mesencephalic neural progenitor cells. Schwann cells are cultured from sciatic nerves of neonatal or adult rats but also from peripheral nerves of human donors. Cultures are analyzed with regard to cell adhesion, viability, proliferation rates as well as cell differentiation (neurite outgrowth) on the different PolySia-based substratum.
Project: In vivo application of polySia-based materials in a rat model of peripheral nerve regeneration - morphological and functional regeneration (DFG-FOR 548 for Prof. Dr. Claudia Grothe)
Soluble PolySia and PolySia-based scaffold materials are evaluated in vivo. PolySia and PolySia-based materials are incorporated into nerve transplants which could be additionally substituted by transplanted Schwann cells. Exemplarily, the incorporation of PolySia-nanofibres and Schwann cells into tubular nerve transplants is depicted. Those biosynthetic nerve transplants are sutured between the stumps of transected sciatic nerves of adult rats to bridge a nerve gap. The outcome of the regeneration process is evaluated by functional and histomorphometrical methods. E.g., electrodiagnostic measurements are carried out in the anaesthetised animals by the end of the experiment to record compound muscle action potentials to determine the nerve conduction velocity. While histomorphometrical analysis of semi-thin cross sections through the regenerated tissue elucidates the number of regenerated myelinated axons.